Conveyor apparatus are widely used in a great variety of industrial fields as part of automated machinery for transporting products or work pieces from one location to another automatically and repetitively with minimal operator control or observation. It is thus important that the conveyor construction be durable and reliable, and if damaged, easily and quickly repairable with readily available parts. Such conveyors in the past have employed chains or collapsible rod and link conveyor belts to which individual ware-supporting attachments are attached. The collapsible rod and link conveyor belt has a conveying surface of open-frame construction formed by spaced rods in generally parallel relationship and extending transversely to the direction of motion of the belt. Typically, the rods are interconnected by two parallel rows of links at the extreme edges of the belt and thus at the opposite ends of the rods.
The present invention is particularly adapted for use in such collapsible rod and link conveyor belts. An example of such a conveyor belt is shown in U.S. Pat. No. 3,225,898 to Gerald C. Roinestad, entitled "Collapsible Conveyor Belt." The conveyor belt of the Roinestad U.S. Pat. No. 3,225,898 includes a supporting surface comprising a plurality of transverse rods and a link construction which enables the conveyor belt to travel through an edgewise arcuate path in the plane of the belt as well as an arcuate path about an axis parallel to the plane of the belt. Chain conveyors typically do not lend themselves to situations requiring the conveyor belt to travel through an edgewise arcuate path in the plane of the belt, for example, a long helical path which requires the inner portion of the belt to collapse upon itself and/or the outer portion of the belt to expand as the belt travels such a path.
Numerous attachments have been used on conveyor apparatus to provide a supporting surface for the wares carried thereon. Non-collapsing attachments are disclosed for conveyors utilizing rods in U.S. Pat. Nos. 1,376,449 (grated support surface); 3,799,328 (grated support surface); 3,977,514 (continuous support surface); and 4,469,221 (grated support surface); and for conveyors utilizing chains in U.S. Pat. No. 4,582,193 (continuous support surface). Collapsing attachments are disclosed for collapsible rod and link-type conveyors in U.S. Pat. Nos. Re. 27,690 (grated support surface); 2,872,023 (grated support surface); 3,261,451 (grated support surface); 3,333,678 (continuous support surface); 3,416,645 (continuous support surface); and 4,394,901 (continuous support surface).
The prior art attachments which provide a collapsible continuous support surface disclose attachments which meet one another along lines generally perpendicular to the direction of relative motion between collapsing attachments when travelling the straight portion of the conveyor. Subsequent expansion and collapsing of the various portions of the respective attachments relative to one another when the conveyor belt travels through an edgewise arcuate path in the plane of the belt imparts tensile forces across a similar line in an article resting upon at least two of such attachments. If the article is pliable or lacks sufficient cohesive strength, for example, a hamburger pattie, undesirable distortion or disassociation of the article may occur resulting in a non-acceptable product for market. Such attachments are considered herein to be tensioning attachments.
The prior art attachments which provide a collapsible grated support noted above are all of a flattened helix of wire. In such conveyor systems, when the belt collapses, the loops of one helix nest between the loops of the next helix. Subsequent expansion of two collapsed attachments under a common article imparts a series of minute shear forces across the article. The likelihood of distortion in the article is less as compared with prior art attachments providing a collapsible continuous support surface. Such attachments are considered herein to be non-tensioning attachments.
Problems associated with the use of flat helical mesh woven onto collapsible rod and link conveyor belts (grid belts) frequently have centered upon the inherent existence of a cavity or hole within each helix, formed by the opposing flat faces of the helix and the connective members extending through the end portions of such flat helixes. In belt structures having such cavities within the helix, it is possible for a relatively small diameter elongated item, e.g., a green bean or a threaded fastener, to slip into such a cavity and become trapped, thus presenting an unsanitary condition or possibly damaging the belt. One technique for avoiding this problem has been the use of a more tightly wound helix to provide a finer mesh. This approach, however, consumes much greater amounts of wire for a belt of given dimensions and renders such a belt both more costly and heavier than desirable, requiring heavier components to support the belt and more power to operate it.
U.S. Pat. No. 3,920,117 issued to Roinestad discloses an attachment which is trap-free as compared to a flat helix, but the attachment is not collapsible. Other trap-free, non-collapsing attachments are disclosed in U.S. Pat. Nos. 3,799,328; 4,469,221; and 4,582,193. Though these are trap-free attachments, they are also tensioning attachments.
A further problem associated with the non-tensioning attachments of the prior art is repair and/or replacement of a damaged or broken flat helix wire. Such a repair or replacement is not easily or readily accomplished. Considerable time and effort is required, resulting in an extended down-time period of the conveyor belt. The foregoing problem stems from the requirement that the flat helix wire be installed onto the rods of the belt prior to assembly of the belt in a given system.
Thus, there exists a need to provide a non-tensioning, trap-free ware-support attachment which can be used in conjunction with commercially available collapsible rod and link conveyor belts, and which is easily attachable and removable from an assembled belt without requiring complete disassembly of the conveyor belt system, the use of special tooling, nor specially skilled labor, while at the same time remaining securely fastened to the rods of the belt while in operation.